CHAPTER III 



STRUCTURE AND DEVELOPMENT OF INSECTS 



THE more experience the farmer has with insect pests, the 

 more he conies to realize that if lie would successfully combat 

 them, he must have a certain amount of necessary knowledge 

 concerning their structure and growth. 



In general, the artificial means which may be effectually 

 used to combat an insect pest will depend more or less upon 

 the anatomical structure of the insect, while control by general 

 methods of culture will depend upon a knowledge of the peculiar- 

 ities of its life-history. The value of a proper understanding of 

 these important factors in insect control is therefore apparent. 



General Structure of an Insect 



The body of an insect is composed of three separate parts, 



the head, thorax, and abdomen 

 (Fig. 14), each of which is com- 

 posed of several rings or segments. 

 To the head are attached the 

 jointed antennae, or feelers, the 

 compound eyes, and the mouth- 

 parts, which are described below. 

 Each of the three segments of 

 the thorax bears a pair of legs, 

 and adult insects usually possess 

 one or two pairs of wings upon the 



FiG.14.-Honey-bee, showing the last two segments of the thorax, 

 three principal regions of the body The abdomen is composed of nine 

 of an insect:-;*, head; ^thorax; segments, but bears no 



abd, abdomen. 



appendages save the ovipositor of 



the females of certain orders. 



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